Traditional techniques for describing and understanding aquatic physical habitat in streams have focused on manual measurements of channel topography. Typically this involves field mapping techniques that can be time-consuming, costly, labor- intensive and limited to infrequent local reach-scale surveys done during low flow conditions. It can be logistically prohibitive to conduct the field surveys at spatial and temporal scales appropriate for some aquatic species. For example, an optimal sampling scheme may be to take repeated measurements at a high frequency along the channel but costs dictate seasonal data collection at select or widely separated sites.
New remote sensing techniques, such as airborne water-penetratingLight Detection and Ranging (LiDAR) and boat-mounted acoustic sensors can produce highly accurate Digital Elevation Models (DEMs) with continuous coverage of long segments of channels and stream networks. Thus, we now have the ability to more nearly inventory, rather than locally sample, the same aquatic habitats. However, we lack automated techniques to analyze these new more-synoptic digital data. The US Forest Service and ESSA Technologies have developed a suite of GIS tools, the River Bathymetry Toolkit (RBT), for processing high resolution DEMs of channels. Our goal is to characterize in-stream and floodplain geomorphology to support aquatic habitat analyses and numerical models of flow and sediment transport. The (RBT) is available for free and is under active development. Tools exist for cutting cross sections and longitudinal profiles into high resolution DEMs to extract hydrologic parameters such as wetted area, bankfull width, hydraulic radius, gradient and sinuosity. It is possible to save the cross section properties as an ESRI Shapefile and then add them to a map. Using an automated detrending algorithm, users are able to remove the overall valley slope. Tools are being created that use the detrended raster to investigate flooding outside a main channel at any prescribed discharge or flow stage. These methods will allow a user to describe the “off-channel” habitat under different flow conditions.
High Resolution Bathymetry of Rivers - Data acquisition with an airborne narrow-beam green lidar. Data interpretation including: basic mapping, frequent domain analyses, hydraulic geometry measurements with a custom-built ArcGIS toolkit.
Disclaimer of Liability
Neither the United States Government nor any of its employees makes any warranty, express or implied, for any purposes regarding the River Bathymetry Toolkit (RBT). This includes warranties of merchantability and fitness for any particular purpose. Furthermore, neither the United States Government nor any of its employees assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information or products derived from the River Bathymetry Toolkit.
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